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This article is intended to demonstrate methods of classifying rings by their primary attributes (metal type, mandrel diameter (MD), ring inner diameter (ID), wire diameter (WD) and resulting aspect ratio (AR), and weight), which make them ideal for chainmail use, and the collection and recording of this information. Also, this article will consider variables which will affect ring sizes, which include springback. Regarding aspect ratios, specifically it will discuss how they affect chainmaillers, and their role in weave studies. Detail is gone into on the proper use of a vernier caliper to measure the wire and inner diameter of a ring type. I highly recommend reading the articles listed at the end of the article to supplement the information provided.

Ring Attributes

There are five basic pieces of information to store about each ring type. These include its metal type, the diameter of the wire used WD), the diameter of mandrel used to make the rings (MD), the measured (actual) ring inner diameter (ID), and the weight of the rings. Type of metal includes the metal itself (such as stainless steel, aluminum, copper, bronze, brass, nickel silver, etc.) as well as the alloy and temper, if that information is available. Wire diameter is usually known when you buy wire. For our purposes, it must be specified using measured units (decimal inches or millimeters) instead of one of the wire gauge systems. This information is usually available through the wire supplier, however, due to wire size tolerances, it's important to measure the wire instead of using the provided data. A ring that is cut off a coil wound on a 5/16" mandrel is classified as a 5/16" ring. Of course, the ring itself will not have an exact inner diameter of 5/16" due to variables that come into play during the ring manufacturing processes. (These variables are explained in the next section.) The ring will have an actual inner diameter which will be slightly greater than the listed value. The actual ring size (inner diameter) will be listed using the same unit as the wire size (decimal inches or millimeters). The weight of a ring type can be stored as either number of rings per pound, or kilogram.

Variables That Affect Actual Ring Size

A ring will almost always be slightly larger than its listed ring size. This is due mainly to a thing called springback.

As defined on zlosk.com, springback is defined as follows:

According to www.dictionary.com, springback refers to: "a flying
back; the resilience of a body recovering its former state by
elasticity; as, the spring of a bow", or, in our case, a coil of wire.
When winding wire on a mandrel into a coil, the coil unwinds a little
bit when tension on the wire is released. This results in the rings
having a slightly larger ring I.D. than originally anticipated. The type
of material used, tension on the wire while coiling and speed of
coiling are some of the factors involved in springback, making it
difficult to come up with a common number that everyone can use.
Material seems to have the greatest impact on springback.

The amount of springback is affected by the following variables:

metal type/alloy/temper

wire thickness

mandrel size

speed and method of coiling

On top of this, the ring cutting method will also have an effect on the actual ring size of the resulting rings. Thus, it is important to control as many ring manufacturing processes as possible for any batch of a specific ring type to ensure consistency. What this boils down to is the fact that one chainmailler's rings of a certain metal type and size will not necessarily be the same as those of another mailler.

Aspect Ratio

A sixth piece of information about a ring type is its aspect ratio. A ring's AR is a calculated number based on the ring inner diameter divided by the wire size. To calculate this, you must use measurements of the same unit (decimal inches or millimeters). Before you can determine the AR of a ring type, you must find its actual wire diameter, and actual inner diameter. These are found by measuring the rings using a caliper.

Measuring Rings

Measuring rings is an activity that will require a special tool called a caliper. Calipers vary in quality and accuracy. In the field of chainmail study, the desired precision should be that of one thousandth of an inch (0.001") or roughly 0.025mm for those who use the metric system. The caliper in the picture (model # DCH-S-6 from Victor Machinery Exchange) measures to this precision. It has a dial readout, and thus is a dial caliper. Some calipers contain an LCD matrix display, and are called digital calipers. If you are planning on getting a caliper for chainmail study, make sure it is one that has the capability of measuring inside diameter as well as the outside measurement of an object. Luckily, most models do.

Measuring Wire Diameter

Hold the ring such that one edge is exposed and put that between the outside caliper jaws. Bring the outside jaws together so that they push against the wire. You can use the wheel on the bottom. Now observe the readout section for your measurement and record. In this situation the ring is made out of .063" wire, and the readout displays this. The dial points to 63, and the number that precedes that is the 0 right next to my thumb.

Measuring Inner Diameter

The mandrel on which this ring was wound measures 5/16", or .3125". To measure the actual inner diameter of a ring, you place it over the inside caliper jaws then pull the caliper out until each jaw touches opposite sides of the inside part of the ring. The dial readout displays 46, and the main scale reads 3, thus the actual inner diameter of this ring is .346"

Collecting and Recording Information

Data was collected and recorded for two ring types for this tutorial to be used as examples. The first ring type (as used in the caliper demonstration) is .063" (1.6mm) 1/4 hard temper, 304 stainless steel, 5/16". The second ring type is .062" (1.6mm) full hard temper, 5356 (bright) aluminum, 3/16". The inner diameter of 25 rings of each type were measured and recorded, then their average found. Measuring just one ring won't necessarily give you accurate data. Even though you are controlling the ring manufacturing processes as much as possible, there are still tolerances experienced. 25 ring types will provide a very accurate average, but might be considered overkill. Some individuals like to measure each ring on two planes and average the difference.

A good tool for recording this type of information is a spreadsheet. That way you can plug in the formulas to find the average inner diameter, and aspect ratio.

With the stainless steel rings used in the demonstration, there is a .008" tolerance between the ring having the smallest measured inner diameter (.343") and that of the largest inner diameter (.351"). The actual inner diameter of the stainless steel rings is .346" vs. the "ideal" inner diameter (measurement of the mandrel used) of .3125", thus the rings are about 10.7% larger than their ideal size. The actual aspect ratio of these rings is 5.5. The aluminum rings bear the same .008" tolerance among the measured inner diameters, and with an actual inner diameter of .205" vs. an ideal inner diameter of .1875", they are about 9.3% larger than their ideal size. The difference in the actual size of a ring and its ideal size will vary according to various factors which, as previously mentioned, include springback (due to metal type, wire size, mandrel size, and coiling method), and ring cutting method.

Significant Digits

Due to the fact that we're dealing with approximate numbers (measurements), we must round the results to the proper number of significant digits. This means using the same number of significant digits as the figure in the equation with the lowest number of significant digits. To calculate the actual aspect ratio in the two cases above, using the equations (.346/.063), and (.205/.062), the wire size only has two significant digits in each case. Thus we round the answer in each case to two significant digits (5.5, and 3.3, respectively).

Weave Studies

One of the main areas where properly measured rings and calculated aspect ratios are very important is in study of chainmail weaves. For every weave, there will be a range of aspect ratios that will work, and at least one range of aspect ratios that won't work. Rings with an aspect ratio that is too small for a weave to be constructed are those which fall below the minimum AR for that weave. In very rare cases with certain weaves, if your rings have an aspect ratio that is too high, the weave will not work (Jens Pind (JPL) is the only well known weave with this constraint). These rings are said to fall above the maximum AR for that particular weave. In most cases, there is no maximum AR for a weave; the larger the AR you use, the looser the weave becomes. Rings sizes that cause a certain weave to either have a desired look, flexibility, or function are said to have an "ideal" or "preferred" AR for the weave. Every weave has an ideal AR range. This will differ significantly from weave to weave.

How do you find the ideal AR for a weave, and/or its practical or absolute minimum AR? One method is to look the information up on the Internet. Just remember to check whether or not the source of the information used measured ring inner diameters, or listed ring diameters (mandrel diameters). Another, and much better method of finding the ideal, practical minimum, and/or absolute minimum AR is through experimentation. This means trying out the weave using various ring types that you've already measured, and recording the information (whether or not the weave works, and how well) for further use.

Scaling Up or Down

Once you have a known aspect ratio information for a particular weave, you can determine what ring size to use if you want to try the weave using a different wire size. As an example, lets say you have found the Full Persian weave made with .063" 5/16" stainless steel rings to be ideal for your use. These rings have an actual aspect ratio of 5.5. If you want to try the weave using .048" wire, then the equation (5.5*.048) will tell you that you need to use rings with an actual inner diameter of about .26". How do you know what ideal inner diameter will yield rings with an actual ID of .26"? By trying to make rings on a mandrel that is slightly smaller than .26". The size of mandrel to use will vary somewhat depending on the metal type you plan on using, due to variance in springback. Let's say for example you plan on using stainless steel. From my personal records, my .048" 1/4" stainless steel rings have an ID of about .278", and my .048" 7/32" stainless steel rings have an ID of roughly .243". Thus I can calculate that if I were to make stainless steel rings using a 15/64" rod out of .048" (I haven't yet, as of this writing), they will have an actual ID of approximately .26", and bear the same approximate AR as the .063" 5/16" stainless steel rings. If your mandrels are in larger increments, you can round up or down as you see fit, bearing in mind that the resulting tightness of the weave will vary accordingly.

Information Storage and Retrieval

Spreadsheet/Table

For most people, storing the ring information should be done on some kind of table, or using a spreadsheet. If a spreadsheet is used, a chart such as this one should be considered:

This way, you can add in data for each new ring type you create, and use formulas to calculate the ideal AR and the actual AR. You will also be able to sort the information by any of the attributes (if you list gets big enough to require this use).

Database

A better way of storing and managing this information is the use of a relational database. I have found that the following table structure provides an adequate means of storing all ring information. The tbl_prefix signifies a table, and the fld_prefix signifies a field.

The sample data from above is presented:

This is actual information that I've stored in my database (except the ID numbers in tbl_metal_type and tbl_ring, which are different). The separate table for wire size is not wholly necessary. The ID field in tbl_mandrel_diameter is an integer which represents the number of 64ths of an inch that equates to that particular ring size. I've done it this way because my mandrel collection is measured in 64ths of an inch increments (as of the writing of this article). The ID field in tbl_wire_size follows the same kind of logic. The ID fields in the two other tables are auto incremented with each new ring type added. If you use different alloys of certain metals, then the metal type table could be broken into two tables. But I'll leave that up to you, should you decide to go that direction.

You will notice that aspect ratios are not stored in the database. The reason for this is due to the fact that they are calculated numbers, based on wire size and actual inner diameter. Thus, they are calculated at the program level. The only place in which aspect ratios would normally be stored in a database is in a weave table if you are recording what aspect ratio works with a particular weave.

Closing

This article covered ring classification by their inherent attributes, as well as the storage of this information. Also presented were discussions on aspect ratios and how they are calculated, as well as the use of a vernier caliper to measure ring sizes.

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